compromise/src/term/noun/makeArticle.js

natural language processing in the browser

'use strict';

//chooses an indefinite aricle 'a/an' for a word
const irregulars = {
  'hour': 'an',
  'heir': 'an',
  'heirloom': 'an',
  'honest': 'an',
  'honour': 'an',
  'honor': 'an',
  'uber': 'an' //german u
};
//pronounced letters of acronyms that get a 'an'
const an_acronyms = {
  a: true,
  e: true,
  f: true,
  h: true,
  i: true,
  l: true,
  m: true,
  n: true,
  o: true,
  r: true,
  s: true,
  x: true
};
//'a' regexes
const a_regexs = [
  /^onc?e/i, //'wu' sound of 'o'
  /^u[bcfhjkqrstn][aeiou]/i, // 'yu' sound for hard 'u'
  /^eul/i
];

const indefinite_article = function(t) {
  let str = t.normal;

  //explicit irregular forms
  if (irregulars.hasOwnProperty(str)) {
    return irregulars[str];
  }
  //spelled-out acronyms
  let firstLetter = str.substr(0, 1);
  if (t.term.isAcronym() && an_acronyms.hasOwnProperty(firstLetter)) {
    return 'an';
  }
  //'a' regexes
  for (let i = 0; i < a_regexs.length; i++) {
    if (str.match(a_regexs[i])) {
      return 'a';
    }
  }
  //basic vowel-startings
  if (str.match(/^[aeiou]/i)) {
    return 'an';
  }
  return 'a';
};

module.exports = indefinite_article;